Marked improvement over Boneshaker in some areas, worse in some others. Not much character development, but a forward-moving plot.
One interesting bit is how it seems that Seattle can be a zombie-infested hell, and because it's far away, *nobody cares*. Heck, they mostly don't know anything about it, they think it's deserted!
The part that is better than Boneshaker is that this has a plot where you can see how it makes sense that the characters do what they do, where in Boneshaker... well, not quite. The part that is worse is that the characters are not even one-dimensional, they are one-phrase. You can describe each in one longish sentence.
"Famous washed out southern spy lady badass, now working for Pinkerton but still loyal to the south, on a mission" and "Escaped slave, now air pirate, with a grudge against those who stole his airship and determined to catch them, kill them and recover his property".
There, that's all they are.